This invention relates to polymer composition blends. In one of its aspects this invention relates to a polymer blend exhibiting synergistic impact resistance. In another of its aspects this invention relates to the production of impact resistant blends of polymeric resin. In still another aspect of this invention it relates to the improvement of the notched Izod impact strength of resinous monovinyl-substituted aromatic compounds/conjugated diene copolymers.
The blending of polyvinylchloride (PVC) with copolymers of monovinyl-substituted aromatic compounds, herein called vinylarene, copolymerized with conjugated diene is known in the art to improve various characteristics of either the PVC or of the vinylarene/conjugated diene copolymer. It has been found, however, that the blending set out in the prior art has incorporated rubbery vinylarene/conjugated diene copolymers into blends with PVC. The rubbery characteristic of the copolymers is obtained by having a preponderance of the conjugated diene comonomer incorporated into the copolymer.
The improvement of impact strength of PVC seems to be associated in the prior art with the addition of rubbery copolymer of conjugated diene and vinylarene to the PVC. In U.S. Pat. No. 3,557,252 blends of 95 to 60 weight percent PVC and 5 to 40 weight percent rubbery butadiene/styrene copolymer exhibit impact strength that is enhanced as compared with either PVC or the rubbery copolymer taken alone. In U.S. Pat. No. 4,161,472 both a rubbery conjugated diene/vinylarene copolymer and a resinous conjugated diene/vinylarene copolymer are added to PVC to provide increase impact strength.
The present invention is interested in blends of resinous conjugated diene/vinylarene copolymer, i.e., copolymer having a preponderance for vinylarene in the copolymer, with up to an equal amount of polyvinylchloride (PVC) to provide a blend having a synergistically enhanced notched Izod impact strength.
It is therefore an object of this invention to provide a polymeric composition blend exhibiting synergistically enhanced notched Izod impact strength. It is another object of this invention to provide a method for producing this composition.
Other aspects, objects and various advantages of this invention will become apparent upon reading the specification and the appended claims.